Correlation Studies on H3+. II. Electron Densities and Expectation Values

Effects of correlation on one‐electron distribution and other properties are calculated for the ${\mathrm{H}}_3^{+}$ molecule ion. Effects due to singly substituted and doubly substituted configurations are essentially additive for this closed shell species. The effect of doubly substituted configurations is to shift charge from the molecular center to nuclear regions, mainly outside the molecule. This is rationalized in terms of the many‐electron theory of Sinanoğlu. The singly substituted configurations cause a slight electronic contraction similar to that caused by initial atomic—molecular formation. Neglect of singly substituted configurations is not justified when one is seeking improvement of properties beyond the HF‐SCF level.